Deployment of valves in transcatheter aortic valve replacement (TAVR) requires a balloon-expandable or self-expandable system. Abdel-Wahab and colleagues assessed the comparative performance of these 2 systems in a randomized trial that enrolled 241 patients scheduled to undergo TAVR. The authors report that the balloon-expandable prosthesis resulted in a greater rate of device success—a composite of successful vascular access, device deployment and retrieval of the delivery system; correct device positioning; performance without moderate or severe regurgitation; and only 1 valve implanted. In an Editorial, Tuzcu and Kapadia discuss factors to consider when choosing a valve for TAVR.

Metformin treatment is associated with improved outcomes after ST-segment elevation myocardial infarction (STEMI) in patients with diabetes. In animal studies, metformin preserves left ventricular (LV) function. In a randomized placebo-controlled trial that enrolled 380 patients without diabetes who underwent primary percutaneous coronary intervention for STEMI, Lexis and colleagues found that compared with placebo, use of metformin (500 mg twice daily for 4 months) did not result in improved LV ejection fraction assessed 4 months after infarction.

In a systematic review and meta-analysis of data from 38 cohort studies, Aune and colleagues assessed the relationship between maternal body mass index (BMI) and risk of fetal death, stillbirth, and neonatal, perinatal, and infant death. The authors found that even modest increases in maternal BMI were associated with increased risk of these outcomes, with the greatest risk observed in the category of severe obesity.

Fibromyalgia—characterized by widespread pain and often accompanied by fatigue, memory problems, and sleep and mood disturbances—has an estimated prevalence of 2% to 8%. In this JAMA Clinical Crossroads article, Clauw discusses the epidemiology, pathophysiology, diagnosis, and evidence-based pharmacologic and nonpharmacologic treatment of this disorder.

High-frequency hearing loss—typically noise-related and preventable—is increasing among adolescents. A study in JAMAOtolaryngology–Head and Neck Surgery reported results of a survey to assess parental knowledge of and perspectives on adolescent hearing loss that found few parents thought their adolescent was at risk and a majority had not discussed noise-related hearing loss with their child. In this From the JAMA Network article, Kesser discusses parent education as an approach to preventing noise-induced hearing loss in children.